Sheet conveyance device and program for sheet conveyance device

ABSTRACT

A sheet conveying apparatus of an embodiment includes a conveyance path along which a sheet can be conveyed, and a plurality of conveyance rollers configured to move a sheet along the conveyance path. A wireless tag reader/writer is configured to read information from, and write information to, a wireless tag of a sheet on the conveyance path. A controller is configured to detect a phase change in response waves received by the wireless tag reader/writer from a wireless tag. The controller is also configured to identify whether a wireless tag is moving along the conveyance path based on the detected phase change in response waves from the wireless tag. The controller controls the wireless tag reader/writer to write information to the wireless tag identified as moving along the conveyance path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/096,723, filed on Nov. 12, 2020, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2020-011484,filed on Jan. 28, 2020, the entire contents of each of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a sheet conveyingapparatus and a program.

BACKGROUND

Conventionally, an image forming apparatus conveys a sheet from a sheetcassette or a manual feeding tray and then forms an image on theconveyed sheet. In some examples, sheets of a certain type incorporate awireless tag (e.g., an RFID tag). In order to read and write informationto and from a wireless tag of such a sheet, the image forming apparatusincorporates a wireless tag communication device along the sheetconveyance path.

A technique of performing reading and writing to tags while theresonance frequency of the transmission antenna is changed such that thefrequency deviation between the resonance frequency of the transmissionantenna and the transmission signal being supplied to the transmissionantenna falls within an allowable range in order to prevent thedeterioration in the antenna communication performance due to a decreasein the resonance current is known.

However, if information is to be written to a wireless tag of a sheetwhile moving on a conveyance path, the communication area of thewireless tag communication apparatus becomes relatively wide. As such,the wireless tag communication device may also inadvertently communicatewith other wireless tags on the sheet or on the conveyance path, and maythus write information to these other wireless tags in error. Forexample, the wireless tag communication device may inadvertently writeinformation to a wireless tag on a sheet that is not yet on theconveyance path, such as a sheet still in a sheet cassette.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic diagram of an image forming apparatus according toan embodiment.

FIG. 2 is a schematic diagram of a sheet flow for double-sided printing.

FIG. 3 is a block diagram of a sheet conveying apparatus according to anembodiment.

FIG. 4 is a schematic diagram depicting phase data stored in a phasestorage portion.

FIG. 5 is a flowchart of a process related to reading and writing ofinformation from and to a wireless tag.

DETAILED DESCRIPTION

According to an embodiment, a sheet conveying apparatus of an embodimentcomprises a conveyance path along which a sheet can be conveyed, and aplurality of conveyance rollers configured to move a sheet along theconveyance path. A wireless tag reader/writer is configured to readinformation from, and write information to, a wireless tag of a sheet onthe conveyance path. A phase change detector is configured to detect aphase change in response waves received by the wireless tagreader/writer from a wireless tag. A tag specifying unit is configuredto identify whether a wireless tag is moving along the conveyance pathbased on the detected phase change in response waves from the wirelesstag. A controller is configured to control the wireless tagreader/writer to write information to the wireless tag identified asmoving along the conveyance path.

A sheet conveyance apparatus of an embodiment can appropriately writeinformation to a wireless tag on a sheet that is being moved along aconveyance path. Hereinafter, an image forming apparatus incorporating asheet conveying apparatus according to an embodiment will be describedas an example.

First, a configuration of the image forming apparatus 10 according to anembodiment will be described with reference to FIG. 1. FIG. 1 depicts animage forming apparatus 10 according to an embodiment.

In FIG. 1, the image forming apparatus 10 includes a control panel 13, awireless tag communication device 201, and a printer unit 18. Theprinter unit 18 includes an image forming controller 100, a sheetcassette 16 a, and a sheet cassette 16 b. The image forming controller100 controls the control panel 13, the wireless tag communication device201, and the printer unit 18. The image forming controller 100 controlsconveyance of sheets in the printer unit 18. In particular, control ofthe conveyance of the sheets is to control the conveyance timing of asheet, the stop position of a sheet, the conveyance speed of a sheet,and the like.

The control panel 13 includes an input key and a display unit. Forexample, the input key accepts input from a user. For example, thedisplay unit is a touch panel type. The display unit receives an inputand displays the input. For example, the control panel 13 displays anitem of information related to the operation of the image formingapparatus 10 on the display unit so as to be able to set or adjustparameters or settings associated with the item. The control panel 13notifies the image forming controller 100 of inputs and changes tosettings made by the user.

The sheet cassettes 16 a and 16 b store sheets on which a wireless tagis provided. The sheet cassettes 16 a and 16 b can also store sheets onwhich a wireless tag is not provided (e.g., a normal or standard sheetof paper or the like). In the following description, unless otherwisespecified, references to a sheet refer to a sheet in or on which awireless tag is provided. For example, a material such as paper or aplastic film can be used as the sheet.

The printer unit 18 performs operations for forming an image on thesheet. For example, the printer unit 18 prints an image corresponding toimage data on a sheet. In the following description, forming an image ona sheet will also be referred to as “printing”. In the presentembodiment, the printer unit 18 is a device for fixing a toner image tothe sheets, but the present disclosure is not limited thereto, and theprinter unit may be an ink jet type device or the like.

In this example, the printer unit 18 includes an intermediate transferbelt 21. The printer unit 18 supports the belt 21 by the driven roller41, the backup roller 40, and the like. The printer unit 18 rotates theintermediate transfer belt 21 in the direction indicated by the arrow min FIG. 1. The printer unit 18 includes four sets of image formingstations 22Y, 22M, 22C, and 22K. The image forming stations 22Y, 22M,22C, and 22K correspond to Y (yellow), M (magenta), C (cyan), and K(black), respectively. The image forming stations 22Y, 22M, 22C and 22Kare arranged on the lower side of the intermediate transfer belt 21 inorder along the rotation direction of the intermediate transfer belt 21.

Hereinafter, the image forming station 22Y of Y (yellow) from among theimage forming stations 22Y, 22M, 22C, and 22K will be described as anexample. The image forming stations 22M, 22C and 22K have the sameconfiguration as that of the image forming station 22Y, and thereforedetailed description thereof will be omitted.

The image forming station 22Y includes an electrostatic charger(charger) 26, an exposure scanning head 27, a developing device 28, anda photosensitive cleaner 29. The charger 26, the exposure scanning head27, the developing device 28, and the cleaner 29 are disposed around thephotosensitive drum 24 that rotates in the direction of the arrow n inFIG. 1.

The image forming station 22Y includes a first transfer roller 30. Thefirst transfer roller 30 is disposed so as to face the photosensitivedrum 24 via the intermediate transfer belt 21.

The charger 26 uniformly charges the photosensitive drum 24. Theexposure scanning head 27 selectively exposes the uniformly chargedphotosensitive drum 24 to form an electrostatic latent image on thephotosensitive drum 24. The developing device 28 develops theelectrostatic latent image on the photosensitive drum 24 by supplying atwo-component developer (formed of a toner and a carrier) to thephotosensitive drum 24.

The first transfer roller 30 transfers the toner image formed on thephotosensitive drum 24 to the intermediate transfer belt 21 (this may bereferred to as a primary transfer). The first transfer roller 30 of eachof the image forming stations 22Y, 22M, 22C, and 22K transfers therespective toner images onto the intermediate transfer belt 21, therebyforming a color toner image on the intermediate transfer belt 21. Thecolor toner image is a toner image formed by sequentially supplyingtoner images of Y (yellow), M (magenta), C (cyan), and K (black). Thecleaner 29 removes the toner remaining on the photosensitive drum 24after the primary transfer.

The printer unit 18 includes a second transfer roller 32. The secondtransfer roller 32 is disposed so as to face the backup roller 40 viathe intermediate transfer belt 21. The second transfer roller 32transfers all of the color toner images on the intermediate transferbelt 21 to the sheet (this may be referred to as a secondary transfer).In the following description, the term “toner image” may refer amulti-color toner image or a toner image of only one color(monochromatic). The toner image may be a toner image formed using adecolorable toner.

The conveyance path 33 is a path through which a sheet is conveyed byconveyance rollers (for example, the conveyance rollers 330 and thelike). In this example, the conveyance path 33 includes a firstconveyance path 33 a, a second conveyance path 33 b, and a thirdconveyance path 33 c. The first conveyance path 33 a is a conveyancepath from a merging portion 44 a to a branch portion 44 b. The secondconveyance path 33 b is a conveyance path passing through the inside ofan inversion unit 38 (also referred to as a reversing unit), and is aconveyance path that is different from the branch portion 44 b to themerging portion 44 a and is different from the first conveyance path 33a. The third conveyance path 33 c is a conveyance path from the branchportion 44 b to a sheet discharge tray 20.

The sheet to be processed can be taken out from any one of the sheetcassette 16 a, the sheet cassette 16 b, or a manual feeding tray 16 c.After being taken out, the sheet is temporarily stopped at a portionwhere the two registration rollers 31 are in contact with each other. Atthis time, the leading edge of the sheet is brought into contact withthe registration roller 31, and any inclination (angling) of the sheetedge is also corrected. The image forming controller 100 starts therotation of the registration roller 31 in accordance with the expectedposition of the toner image on the rotating intermediate transfer belt21, and thus moves the sheet to the position of the second transferroller 32 at an appropriate timing to receive the toner image from theintermediate transfer belt.

That is, the toner image formed on the intermediate transfer belt 21 issecondarily transferred to the sheet at the second transfer roller 32.Subsequently, the transferred toner image is fixed to the sheet by afixing device 34. In this way, an image is formed (printed) on the sheetunder the control of the image forming controller 100. The image formingcontroller 100 then conveys the printed sheet to the third conveyancepath 33 c, and discharges the sheet.

The wireless tag communication device 201 includes an arithmetic device,a storage device, and an antenna. The wireless tag in this example, is aradio frequency identifier (RFID) tag. The wireless tag communicationdevice 201 transmits radio waves along the arrow k direction depicted inFIG. 1. The wireless tag communication device 201 is able to communicatewith a wireless tag provided in a sheet being conveyed. Specifically,the wireless tag communication device 201 reads information from thewireless tag and writes information to the wireless tag.

The information written to the wireless tag includes, for example,information indicating an identification of the printed sheet/document,information indicating an intended destination of the sheet/document,and/or contents printed on the sheet/document for when the sheet issubsequently distributed or the like. In the present embodiment, thewireless tag communication device 201 uses, for example, a radio wavesystem (UHF) in the 900 MHz band. However, the communicationmethod/protocol and the frequency band are not limited, and othermethods and frequency bands may be employed in other examples.

Next, double-sided printing operations will be described.

FIG. 2 is an explanatory diagram illustrating an example of double-sidedprinting.

In the case of the double-sided printing, the sheet 250 is taken outfrom any one of sheet feeding locations, such as the sheet cassette 16a, the sheet cassette 16 b, or the manual feeding tray 16 c. The sheet250 is then conveyed to the first conveyance path 33 a. Morespecifically, the sheet 250 fed from one of the sheet feeding locationsis corrected in inclination at the registration roller 31. Then, thesheet 250 is conveyed to the position of the second transfer roller 32to match with the position of the toner image formed on the intermediatetransfer belt 21. The toner image formed on the intermediate transferbelt 21 is transferred to the front side of the sheet 250 by the secondtransfer roller 32. Then, the toner image on the front side of the sheet250 is fixed by the fixing device 34.

The sheet 250 on which the image has been formed on the front side nextenters the third conveyance path 33 c. Then, under the control of theimage forming controller 100, the sheet 250 is switched back andconveyed to the second conveyance path 33 b. Thereafter, the sheet 250is conveyed to the merging portion 44 a via the second conveyance path33 b in the inversion unit 38. The sheet 250 is next conveyed to thefirst conveyance path 33 a via the registration roller 31. Accordingly,the sheet 250 passing through the second conveyance path 33 b isconveyed to the first conveyance path 33 a so that the back surface sidenow faces toward the intermediate transfer belt 21 side.

Then, a toner image formed on the intermediate transfer belt 21 istransferred to the back surface side of the sheet 250 by the secondtransfer roller 32. The toner image transferred to the back surface sideof the sheet 250 is fixed by the fixing device 34. Then, the sheet 250is supplied to the third conveyance path 33 c, and is sent out to thesheet discharge tray 20.

Next, a sheet conveying apparatus 50 included in the image formingapparatus 10 will be described with reference to FIG. 3. FIG. 3 is ablock diagram illustrating an example of a functional configuration ofthe sheet conveying apparatus 50 according to an embodiment.

In FIG. 3, the sheet conveying apparatus 50 includes an image formingcontroller 100, a wireless tag communication device 201, a storagedevice 220, and a conveyance path 33. The image formation control unit100 controls the wireless tag communication device 201 in accordancewith a sheet conveyance program stored in the storage device 220.

The image forming controller 100 is realized by, for example, a centralprocessing unit (CPU), an application specific integrated circuit(ASIC), or the like. The storage device 220 is realized by a read onlymemory (ROM), a random access memory (RAM), a hard disk drive (HDD), asolid-state drive (SSD), or the like.

The wireless tag communication device 201 attempts to read anidentification code (ID) of a wireless tag 251 (provided in a sheet 250)within a communication area at a certain, fixed interval (for example,at a 10 msec interval). Specifically, the wireless tag communicationdevice 201 transmits a signal (carrier wave) at a predeterminedinterval. When a wireless tag 251 in the communication area receives asignal from the wireless tag communication device 201, the wireless tag251 receives electric power from this signal and starts up. The wirelesstag communication device 201 can be a wireless tag reader/writer device.Then, the wireless tag 251 transmits a response wave including the ID ofthe wireless tag communication device 201 previously written orotherwise stored in the wireless tag 251. Accordingly, the wireless tagcommunication device 201 receives a response wave from the wireless tag251 and acquires the ID data corresponding to the wireless tag 251 ID.

The wireless tag communication device 201 is capable of communicatingwith the image forming controller 100. The wireless tag communicationdevice 201 receives a response wave from the wireless tag 251 providedin the sheet 250 at regular intervals and transmits phase dataindicating the phase of the received response wave to the imageformation controller 100.

The image forming controller 100 includes an acquisition unit 101, adetect unit 102, a specifying unit 103, and a communication controller104. The respective units 101 to 104 are not limited to being providedwithin the image forming controller 100 and may be provided in anothercontrol unit (another CPU, an ASIC, or the like) different from theimage forming controller 100.

The acquisition unit 101 acquires the phase data of the response wavereceived from the wireless tag 251 by the wireless tag communicationdevice 201. More specifically, the acquisition unit 101 acquires thephase data of the response wave from the wireless tag communicationdevice 201 at a certain interval (for example, at a 10 msec interval).The acquisition unit 101 starts acquisition of the phase data every timea sheet 250 begins to be printed.

The acquisition unit 101 stores the acquired phase data of the responsewaves in a phase storage portion 221 of the storage device 220 for eachinterval (for example, at a 10 msec interval). Here, when the sheet 250(more particularly, the wireless tag 251 of the sheet 250) moves, thephase of the response wave from the wireless tag 251 changes. Forexample, the response wave from a sheet 250 (the wireless tag 251therein) moving on the first conveyance path 33 a tends to changeaccording to a common change pattern of specific phases. On the otherhand, if a sheet 250 (wireless tag 251) is not moved, the phase of theresponse wave from the wireless tag does not change substantially.

In addition, in the present embodiment, the information can be writtento the wireless tag 251 while the sheet 250 is moving through theconveyance path 33. Therefore, the communication area of the wirelesstag communication device 201 needs to be set relatively wide. Morespecifically, the communication area of the wireless tag communicationdevice 201 is a wider than would be the case if the sheet 250 could becompletely stopped and information written to the wireless tag 251 onlywhile the sheet is stationary at a specific location. For this reason,if information is to be written to the wireless tag 251 while the sheet250 is moving along the conveyance path 33, the potential forinformation to be inadvertently written to another wireless tag 251within the communication area instead of the intended target wirelesstag 251 to which the information is to be written increases.

Therefore, to compensate for this increase potential for inadvertentwriting, the detect unit 102 refers to the phase data stored in thephase storage portion 221, and detects a phase change amount of theresponse wave acquired from wireless tags 251 within the communicationarea at regular intervals. The phase change amount is, for example, avalue indicating a difference in phase acquired at different times froman initial, previous, or reference time. More specifically, in thisexample, the phase change amount is a difference between the responsewave phases stored at a timing interval of 10 msec.

The specifying unit 103 identifies a wireless tag 251 to be read/written(hereinafter referred to as a “target wireless tag 251 a”) based on theamount of phase change of the response wave detected by the detect unit102. Specifically, when the phase change amount of the response wave isequal to or larger than some predetermined value (for example, 10°), thespecifying unit 103 specifies the wireless tag 251 for which such aphase change amount is obtained as the target wireless tag 251 a.

A wireless tag 251 (the target wireless tag 251 a) for which the phasechange amount of the response wave is equal to or more than thepredetermined value is considered to be on a sheet 250 is being movedalong some portion of the conveyance path 33 (for example, the firstconveyance path 33 a). Accordingly, the specifying unit 103 can identifythe wireless tag 251 being moved as the target wireless tag 251 a.

The communication controller 104 controls the wireless tag communicationdevice 201 so as to write information to the target wireless tag 251 aas specified by the specifying unit 103. The wireless tag communicationdevice 201 writes information to the target wireless tag 251 a inaccordance with the control of the communication controller 104.

(Comparison of Change Patterns of the Phase of the Response Wave)

A reference value storage portion 222 stores in advance a referencevalue of the phase of the response wave when the sheet 250 moves on theconveyance path (hereinafter referred to as a “phase reference value”).Specifically, the phase reference value is a change pattern (referencepattern) of the phase of the response wave associated with the normalconveyance of a sheet 250. In the present embodiment, the referencepattern is, for example, a change pattern that increases by 20° for each10 msec.

The phase reference value can be obtained by conveying one test sheet250 in an environment in which other wireless tags 251 are not presentaround the sheet. For example, such phase reference value(s) can beprovided before shipment of the image forming apparatus 10 from afactory or the like. The phase reference value is, for example, a valuethat can be different for different image forming apparatuses 10. Thephase reference value is not necessarily required to be a factorysetting, and for example, the phase reference value may be obtained byprompting a user to obtain a reference value by operation of the imageforming apparatus 10 during a user setup mode or the like.

The specifying unit 103 identifies the target wireless tag 251 a basedon the result of the comparison between the phase change amount detectedby the detect unit 102 and the phase reference value stored in thereference value storage portion 222. Specifically, for example, thespecifying unit 103 compares the change pattern indicated by the phasechange amount detected by the detect unit 102 with the reference patternstored in the reference value storage portion 222. As a result of thecomparison, the specifying unit 103 is able to identify a particularwireless tag 251 that has output a response wave corresponding to thephase reference pattern as the target wireless tag 251 a when thedetected and reference patterns are approximately the same.

(Control of Wireless Tags 251 which are not Subject to Reading andWriting)

Further, the specifying unit 103 identifies a non-target wireless tag251 (hereinafter referred to as a “non-target wireless tag 251 b”) thatis not a target for reading and writing, based on the phase changeamount detected by the detect unit 102. The non-target wireless tag 251b is, for example, a wireless tag 251 provided in a sheet 250 still inthe sheet cassettes 16 a, 16 b, or on the manual feed tray 16 c.

The communication controller 104 requests the non-target wireless tag251 b specified by the specifying unit 103 to suppress the output ofresponse waves. More specifically, the communication controller 104controls the wireless tag communication device 201 to transmit aresponse suppression command to the non-target wireless tag 251 b forsuppressing the output of response waves. In response to this responsesuppression command, the non-target wireless tag 251 b turns on aresponse suppression flag for prevent the output of a response wave fromthe non-target wireless tag 251 b until subsequent commands.

The response suppression flag can be reset by cutting off the output ofradio waves from the wireless tag communication device 201. The outputof radio waves from the wireless tag communication device 201 is thuscut every time a new printing of a sheet 250 is to be performed. Thus,the response suppression flag can be reset every time the printing of asheet 250 is performed.

(A Position to Write Information to the Target Wireless Tag 251 a)

In some examples, the position at which the information is written tothe target wireless tag 251 a may be set to be on the first conveyancepath 33 a, but in the present embodiment, this position is on the secondconveyance path 33 b. In the present embodiment, the conveyance path 33includes a first conveyance path 33 a, a second conveyance path 33 b,and a third conveyance path 33 c, which may be considered portionsand/or branches of the overall conveyance path 33.

The first conveyance path 33 a is the portion of the conveyance path 33used for forming an image on a sheet 250. The first conveyance path 33 acan be used for performing a front surface printing on a sheet 250 feddirectly from one the cassettes 16 a, 16 b, but may also be used for aback surface printing on a sheet 250 returned via the inversion unit 38.The second conveyance path 33 b is the path by which a sheet 250 isreturned through the inversion unit 38 after previously passing throughthe first conveyance path 33 a. In this example, the second conveyancepath 33 b is a position closer to the wireless tag communication device201 than is the first conveyance path 33 a.

The detect unit 102 is used to detect the phase change amount in theresponse wave from sheets 250 traveling along the first conveyance path33 a. The specifying unit 103 identifies a target wireless tag 251 abased on the phase change amount(s) detected by the detect unit 102. Thecommunication controller 104 controls the wireless tag communicationdevice 201 to write the information to the target wireless tag 251 awhen the target wireless tag 251 a identified by the specifying unit 103moves to the second conveyance path 33 b.

The communication controller 104 determines whether or not the sheet 250with the target wireless tag 251 a has moved to the second conveyancepath 33 b. The communication controller 104 may determine that the sheet250 with the target wireless tag 251 a has moved to the secondconveyance path 33 b based on, for example, the timing of switchingfunctions along the conveyance path 33 for switch back (inversion)processing.

The sheet 250 on the second conveyance path 33 b is subsequentlyreturned to the first conveyance path 33 a again. When a single-sidedprinting is set, backside printing (second printing) is not performed onthe sheet 250 returned to the first conveyance path 33 a. However, whenthe backside printing is set to be performed, the backside printing isperformed.

(Phase Data Example Stored in the Phase Storage Portion 221)

FIG. 4 is an explanatory diagram illustrating an example of phase datastored in the phase storage portion 221. As illustrated in FIG. 4, phasedata 400 includes items corresponding to an “Index”, an “elapsed time”,a “tag ID”, and a “Phase”.

“Index” items are information (e.g. an index number or a counting value)for identifying each piece of data. The “elapsed time” is the elapsedtime since the start of a printing operation corresponding to when theparticular tag ID and phase value were detected. For example, the timeelapsed since the wireless tag communication device 201 transmits thefirst signal (carrier wave) in the printing operation can be used as theelapsed time value. The “tag ID” value is unique identificationinformation allocated for each of the different wireless tags 251. Inthis context, “Phase” information indicates a detect phase value (0° to180°) for a response wave.

In the phase data 400 depicted in FIG. 4, wireless tags 251 twodifferent “tag IDs”, “AAAABBBB0001” and “CCCCDDDD0002,” are illustrated.That is, FIG. 4 shows that two different “tag IDs” corresponding to twodifferent the wireless tags 251 are in the communication area. Whenthere are 3 or more types of “tag IDs” in the communication area of thewireless tag communication device 201. The phase data 400 can include“tag IDs” corresponding to any number of wireless tags 251 detected inthe communication area, but here only two different tags 251 arerepresented in FIG. 4.

Next, the phase change amount of the wireless tag 251 having the tag ID“AAAABBBB0001” will be described. As indicated at the value “1” in the“Index” column, the “Phase” of the response wave of the wireless tag 251with the tag ID “AAAABBBB0001” at elapsed time of 0 msec is 20°. Asindicated at the value “3” in the “Index” column, the “Phase” of theresponse wave of the wireless tag 251 with the tag ID “AAAABBBB0001” at10 msec is 40°. Thus, the phase change amount for the response wave ofthe wireless tag 251 with the tag ID AAAABBBB0001 is +20° from 0 msec to10 msec. This phase change amount (magnitude change) is equal to orlarger than a predetermined value (for example, 10°) indicatingtravel/movement of the wireless tag 251.

As indicated by value “5” in the “Index” column, the “Phase” of theresponse wave of the wireless tag 251 with the tag ID “AAAABBBB0001” atthe 20 msec is 60°. For this reason, the phase change amount of theresponse wave of the wireless tag 251 with the tag ID “AAAABBBB0001”from 10 msec to 20 msec is again+20° (magnitude change of 20°).

The phase change amount is again equal to or larger than thepredetermined value (for example, 10°). That is, the wireless tag 251(“AAAABBBB0001”) is estimated to be a wireless tag 251 on a sheet 250being moved. The comparison between the phase change amount and thepredetermined value is, for example, a comparison of absolute values.The phase change pattern obtained from the phase change amounts overtime for a particular wireless tag 251 can be compared to a referencepattern stored in the reference value storage portion 222, for example.

Accordingly, it can be estimated that the sheet 250 with the wirelesstag 251 having the tag ID “AAAABBBB0001” is moving along the conveyancepath 33. Therefore, the specifying unit 103 identifies the wireless tag251 having the tag ID “AAAABBBB0001” as target wireless tag 251 a.

Next, the phase change amount of the wireless tag 251 having the tag ID“CCCCDDDD0002” will be described. As indicated by value “2” in the“Index” column, the “Phase” of the response wave of the wireless tag 251with the tag ID “CCCCDDDD0002” at 1 msec is 162°. As indicated by value“4” in the “Index” column, the “Phase” of the response wave of thewireless tag 251 with the tag ID “CCCCDDDD0002” at 11 msec is 161°.Therefore, the phase change amount of the response wave of the wirelesstag 251 with the tag ID “CCCCDDDD0002” from 1 msec to 11 msec is −1°(the absolute size change is 1′). This amount of phase change is lessthan the predetermined value (for example, 10°).

As indicated by the value “6” in the “Index” column, the “Phase” of thewireless tag 251 with the tag ID “CCCCDDDD0002” at the 21 msec is 163degrees. Thus, the amount of phase change in the response wave of thewireless tag 251 with the tag ID “CCCCDDDD0002” from 11 msec to 21 msecis +2° (the absolute size is 2°). The amount of phase change is lessthan the predetermined value (for example, 10°). The difference in thedetected phase change amount is presumably due to a minor error inmeasurement or the like. That is, it can be considered that there hasbeen almost no change in the phase change amount for the wireless tag251 with the tag ID “CCCCDDDD0002”.

Accordingly, it can be estimated that the sheet 250 with the wirelesstag 251 having the tag ID “CCCCDDDD0002” is not on the conveyance path33. More specifically, it can be estimated that the sheet 250 with thewireless tag 251 having the tag ID “CCCCDDDD0002” is in one of the sheetcassettes 16 a, 16 b, or on the manual feed tray 16 c. Therefore, thespecifying unit 103 identifies the wireless tag 251 having the tag ID“CCCCDDDD0002” as the non-target wireless tag 251 b.

(Processing Related to Reading and Writing of Information with theWireless Tag 251 Performed by the Image Forming Apparatus 10)

Next, an example of processing related to reading and writing ofinformation from and to the wireless tag 251 performed by the imageforming apparatus 10 (or more particularly a sheet conveyance device 50)will be described with reference to FIG. 5. FIG. 5 is a flowchartillustrating an example of a process related to reading and writing ofinformation with respect to the wireless tags 251 as performed by theimage forming apparatus 10.

In FIG. 5, the image forming apparatus 10 determines whether a printinghas been started (ACT501). The printing in this context is, for example,a printing on a single sheet 250. The image forming apparatus 10 waits(ACT501: NO) until the start of printing. When the image formingapparatus 10 starts the printing (ACT501: YES), the image formingapparatus 10 starts RFID reading (ACT502). Specifically, the imageforming controller 100 controls the wireless tag communication device201 to start transmission of a carrier wave signal at regular intervalsand begins reception of any response wave(s).

Then, the image forming apparatus 10 determines whether or not thewireless tag 251 has been detected (ACT503). In ACT503, specifically,the image forming controller 100 determines whether or not the wirelesstag communication device 201 has received a response wave from awireless tag 251. When the wireless tag communication device 201 doesnot detect any wireless tag 251, the image forming apparatus 10 standsby (ACT503: NO). When the wireless tag communication device 201 detectsa wireless tag 251 (ACT503: YES), the image forming apparatus 10 storesthe relevant data items (that is, values for the “elapsed time”, “tagID”, and “Phase”) of the phase data 400 as obtained by receiving theresponse wave from a wireless tag 251.

Then, the image forming apparatus 10 detects, measures, or calculatesthe phase change amount for a wireless tag 251 indicated by a previouslyreceived tag ID (ACT505) if available. Then, the image forming apparatus10 determines whether or not the phase change amount is equal to orlarger than some predetermined value (ACT506). When the phase changeamount is equal to or larger than the predetermined value (ACT506: YES),the image forming apparatus 10 proceeds to ACT508. When the phase changeamount is not equal to or larger than the predetermined value (ACT506:NO), the image forming apparatus controls the wireless tag communicationdevice 201 to transmit a response suppression command addressed to theparticular (estimated as none moving) wireless tag 251 (ACT507), andreturns to ACT503.

Then, the image forming apparatus 10 compares the phase change patternfor a particular wireless tag estimated as possibly moving in the priorstep(s) with the reference pattern stored in the reference value storageportion 222 (ACT508). Next, the image forming apparatus 10 determineswhether or not the phase change pattern matches, or substantiallycoincides with, the reference pattern (ACT509). When the phase changepattern does not match the reference pattern (ACT509: NO), the imageforming apparatus 10 returns to ACT507.

When the phase change pattern matches the reference pattern (ACT509:YES), the image forming apparatus 10 next determines whether or not thesheet 250 having the wireless tag 251 has been passed to the secondconveyance path 33 b (ACT510). A sheet 250 passing through the secondconveyance path 33 b can be determined, for example, by detecting thatthe entire sheet 250 has passed the branch portion 44 b and beingconveyed to the second conveyance path 33 b by switching back the sheet250.

The image forming apparatus 10 waits until the sheet 250 is on thesecond conveyance path 33 b (ACT510: NO). When the sheet 250 is deemedon the second conveyance path 33 b (ACT510: YES), the image formingapparatus 10 controls the wireless tag communication device 201 to writeinformation to the wireless tag 251 (ACT511).

Then, the image forming apparatus 10 determines whether or not theprinting is finished (ACT512). The image forming apparatus 10 stands byuntil the printing is completed (ACT512: NO). Once the printing isfinished (ACT512: YES), the image forming apparatus 10 controls thewireless tag communication device 201 to reset the communication withthe wireless tags 251 (ACT513), and ends the present series ofprocesses.

By resetting the communication with the wireless tags 251, theoutputting of radio waves from previously suppressed wireless tags 251is reset since the response suppression flag in any of the wireless tags251 is reset. The collected phase data 400 can also be reset by thereset of the communication with the wireless tag 251.

In the flowchart illustrated in FIG. 5, the processing of the ACT506(determination of the amount of phase change) and the processing of theACT508 and ACT509 (the comparison of the change pattern to a referencepattern) are performed, but the processing is not limited to this. Forexample, the processes may be performed together or just one of theprocesses may be performed.

According to the embodiment described above, the wireless tagcommunication device 201 can be controlled so that the target wirelesstag 251 a is first identified based on the phase change amount of theresponse wave and then the information is written to the target wirelesstag 251 a. Accordingly, the sheet conveyance device 50 can appropriatelywrite information to the intended wireless tag 251 of a sheet 250actually moving on the conveyance path 33. That is, erroneous(unintended) writing of information to a wireless tag 251 of a sheet 250in the sheet cassettes 16 a, 16 b, or on the manual feed tray 16 c canbe avoided.

In addition, in the present embodiment, the sheet conveyance apparatus50 specifies the target wireless tag 251 a based on a result of thecomparison between the phase change pattern of the response wave outputfrom the wireless tag 251 and a reference pattern for the phase of theresponse wave of a sheet 250 moved on the conveyance path 33.Accordingly, it is possible to more accurately identify a sheet 250moving on the conveyance path 33, and thus it is possible to moreappropriately write information to the wireless tag 251 of the sheet 250that moves on the conveyance path 33.

In addition, in the present embodiment, the sheet conveyance device 50specifies the non-target wireless tag(s) 251 b on the basis of the phasechange amount of the response wave output from the wireless tag 251, andcontrols the non-target wireless tag(s) 251 b to suppress the output ofa response wave. Accordingly, it is possible to prevent a response wavefrom being output from the wireless tag 251 that is not required. Here,if the wireless tag communication device 201 receives a response wavefrom a wireless tag 251 that is not targeted for writing, an operationof reading the ID of the wireless tag 251 is still performedaccordingly, and the operation of reading the ID of a wireless tag 251may still require an interval longer than, for example, 10 msec toperform associated processing.

However, according to the present embodiment, it is possible to suppressthe output of the unnecessary response wave from the untargeted wirelesstags 251, and therefore, it is possible to prevent unnecessaryoperations associated with reading the ID of such wireless tags 251. Inother words, it is possible to suppress the processing load (and delays)related to the reception of the unnecessary response waves by thewireless tag communication device 201. Therefore, it is possible to moreappropriately detect the phase changes of the response wave(s), and thusit is possible to more appropriately write the information to theintended wireless tag 251 of a sheet 250 moving on the conveyance path33.

In the present embodiment, the sheet conveyance device 50 specifies thenon-target wireless tag 251 b based on the phase change amount of theresponse wave while on the first conveyance path 33 a, and then writesthe information to the wireless tag 251 when the sheet 250 moves to thesecond conveyance path 33 b. Accordingly, it is possible to secure aperiod for detecting the phase change amount of the response wave on thefirst conveyance path 33 a. That is, it is possible to appropriatelydetect the phase change amount of the response wave. Therefore, it ispossible to more accurately determine that a particular sheet 250 ismoving on the conveyance path 33. In addition, it is possible to securea period in which information is written to the wireless tag 251 when onthe second conveyance path 33 b. Therefore, it is possible toappropriately write information to the wireless tag 251 of the sheet 250while on the second conveyance path 33 b.

In the present embodiment, the first conveyance path 33 a is first usedfor performing front surface printing, and the second conveyance path 33b is used for performing the back surface printing (that is, theconveyance path 33 b is the sheet reversing or return path). This makesit possible to efficiently write information to the wireless tag 251 ofa moving sheet 250 using an existing conveyance path 33 withoutseparately providing a conveyance path specifically dedicated to readingand writing information to and from the wireless tag 251.

In the present embodiment, the second conveyance path 33 b is at aposition closer to the wireless tag communication device 201 than thefirst conveyance path 33 a. Accordingly, it is possible to shorten thecommunication distance to the wireless tag 251, and thus it is possibleto more appropriately write the information to the wireless tag 251 ofthe sheet 250 on the second conveyance path 33 b.

The function(s) of a sheet conveying apparatus 50 in the above-describedembodiment may be realized by a computer. In this case, a program forrealizing the function(s) may be recorded in a non-transitory,computer-readable recording medium, and the program recorded in therecording medium may be loaded into a computer system and then executedby the computer system. In this context, a “computer system” includes,for example, an operating system, hardware, a peripheral device, and thelike. A “computer-readable recording medium” refers to a portable mediumsuch as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, anda storage device such as a hard disk built in the computer system.Further, the “computer-readable recording medium” may include acloud-based storage system or the like and a program can be transmittedvia a network such as the Internet or a communication line such as atelephone line from a computer system serving as a server or a client.The program may be a program for realizing a part of the functionsdescribed above or may be a program for realizing the above-describedfunctions in combination with a program already recorded in the computersystem.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed:
 1. A sheet conveying apparatus, comprising: a sheetcassette configured to store a sheet on which a wireless tag can beprovided; a plurality of conveyance rollers configured to move the sheetalong a conveyance path; a wireless tag reader/writer configured to readinformation from, and write information to, the wireless tag on thesheet while on the conveyance path; and a controller configured to:detect a phase change in response waves received by the wireless tagreader/writer from the wireless tag, identify whether the wireless tagis moving along the conveyance path based on the detected phase changein response waves from the wireless tag, and control the wireless tagreader/writer to write information to the wireless tag identified asmoving along the conveyance path.
 2. The sheet conveying apparatusaccording to claim 1, wherein the controller is configured to identifywhether the wireless tag is moving along the conveyance path bycomparison of the detected phase change in response waves from thewireless tag to a previously stored reference pattern corresponding tophase changes in response waves for a wireless tag moving along theconveyance path.
 3. The sheet conveying apparatus according to claim 1,wherein the controller is configured to identify a wireless tag that isnot moving along the conveyance path by a lack of phase change inresponse waves from the wireless tag over intervals of time.
 4. Thesheet conveying apparatus according to claim 3, wherein the wireless tagreader/writer is configured to output a response suppression signaladdressed to the wireless tag identified by the controller as not movingalong the conveyance path.
 5. The sheet conveying apparatus according toclaim 1, wherein the conveyance path comprises a first portion alongwhich an image is transferred to the sheet in a printing operation, anda second portion along which the sheet travels to be returned to thefirst portion.
 6. The sheet conveying apparatus according to claim 5,wherein the second portion is closer to the wireless tag reader/writerthan is the first portion.
 7. The sheet conveying apparatus according toclaim 6, wherein the controller is configured to cause the wireless tagreader/writer to write information to an identified wireless tag whilethe identified tag is on the second portion of the conveyance path. 8.The sheet conveying apparatus according to claim 1, wherein the wirelesstag is an RFID tag.
 9. An image forming apparatus, comprising: a firstconveyance path portion along which a sheet can be conveyed past atransfer roller at which an image can be transferred to a surface of thesheet; a second conveyance path portion along which a sheet from thefirst conveyance path portion can be returned to the first conveyancepath portion for an image to be transferred to another surface of thesheet; a wireless tag reader/writer configured to read information fromand write information to a wireless tag of a sheet in the image formingapparatus; and a controller configured to: detect a phase change inresponse waves received by the wireless tag reader/writer from awireless tag, identify whether a wireless tag is moving along the firstconveyance path portion based on the detected phase change in responsewaves from the wireless tag, and control the wireless tag reader/writerto write information to the identified wireless tag while the wirelesstag is moving along the second conveyance path portion.
 10. The imageforming apparatus according to claim 9, wherein the controller isconfigured to identify whether the wireless tag is moving along thefirst conveyance path portion by comparison of the detected phase changein response waves from the wireless tag to a previously stored referencepattern corresponding to phase changes in response waves for a wirelesstag moving along the first conveyance path portion.
 11. The imageforming apparatus according to claim 9, wherein the controller isconfigured to identify a wireless tag that is not moving along the firstor second conveyance path portion by a lack of phase change in responsewaves from the wireless tag over intervals of time.
 12. The imageforming apparatus according to claim 11, wherein the wireless tagreader/writer is configured to output a response suppression signaladdressed to the wireless tag identified by the controller as not movingalong the first or second conveyance path portion.
 13. The image formingapparatus according to claim 9, wherein the second conveyance pathportion is closer to the wireless tag reader/writer than is the firstconveyance path portion.
 14. The image forming apparatus according toclaim 9, wherein the wireless tag is an RFID tag.